We plan to synthesize a variety of beta-Lactams which have two or more special structural features of the small number of known beta-Lactamase inhibitors. Most of the projected compounds will be prepared by annelation of an appropriate imino compound with an acid chloride (or equivalent). We have developed a convenient synthesis of alpha, alpha-dihalo -beta-lactams which can serve as intermediate for cis or trans-3-halo-2-azetidinones or 3-unsubstituted-2-azetidinones. We have also developed a new synthesis of 3-hydroxy-2-azetidinones which involves the preparation of 3-allyloxy-2-azetidinone and subsequent rearrangement catalyzed by palladium. The alpha-hydroxy-beta-lactams so obtained will serve as intermediates for the preparation of 3-halo-2-azetidinones.